package org.apache.lucene.search.spans;

/**
 * Copyright 2005 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermPositions;

import java.io.IOException;

/**
 * Expert: Public for extension only
 */
public class TermSpans implements Spans {
	protected TermPositions positions;
	protected Term term;
	protected int doc;
	protected int freq;
	protected int count;
	protected int position;

	public TermSpans(TermPositions positions, Term term) throws IOException {

		this.positions = positions;
		this.term = term;
		doc = -1;
	}

	public boolean next() throws IOException {
		if (count == freq) {
			if (!positions.next()) {
				doc = Integer.MAX_VALUE;
				return false;
			}
			doc = positions.doc();
			freq = positions.freq();
			count = 0;
		}
		position = positions.nextPosition();
		count++;
		return true;
	}

	public boolean skipTo(int target) throws IOException {
		// are we already at the correct position?
		if (doc >= target) {
			return true;
		}

		if (!positions.skipTo(target)) {
			doc = Integer.MAX_VALUE;
			return false;
		}

		doc = positions.doc();
		freq = positions.freq();
		count = 0;

		position = positions.nextPosition();
		count++;

		return true;
	}

	public int doc() {
		return doc;
	}

	public int start() {
		return position;
	}

	public int end() {
		return position + 1;
	}

	public String toString() {
		return "spans("
				+ term.toString()
				+ ")@"
				+ (doc == -1 ? "START" : (doc == Integer.MAX_VALUE) ? "END"
						: doc + "-" + position);
	}

	public TermPositions getPositions() {
		return positions;
	}
}
